The present invention relates to a hydraulically powered repetitive impact device and more specifically to a hydraulic demolition hammer.
Such devices serve to deliver successive blows to a variety of tools in order to disintegrate concrete, rock or other materials or for performing work requiring repetitive impact blows, such as riveting and hammering.
Repetitive impact devices are well known in the prior art and have heretofore been predominately driven by air pressure. Lately, several of these devices have been driven hydraulically by oil pressure, but these hydraulically driven devices are notorious for their complexity, requiring a large number of moving parts which makes maintenance expensive, frequent and cumbersome.
Typical examples of such prior art devices are shown in U.S. Pat. Nos. 4,018,135; 3,866,690; 3,827,507; 3,766,830; 3,687,008 and 3,664,435.
Of these prior art devices, U.S. Pat. No. 4,018,135 is perhaps the most typical and one skilled in the art will immediately observe the complex nature of its design requiring intricate machining and sealing operations because of its designer's insistance on using only two hydraulic pressures and of having effective hydraulic areas proportioned such that hydraulic fluid continually biases the sleeve valve toward the piston portion of the hammer member to tend to maintain sealing engagement between the sleeve valve and the piston portion.
In contrast, the present invention has as its principal object, the provision of a hydraulic hammer which has an absolute minimum number of moving parts as compared to prior art devices and which effectively utilizes a multiplicity of hydraulic pressures to eliminate intricately machined moving parts.
It is a further object of the present invention to provide a hydraulic hammer which can deliver an impact force which is from three to ten times higher than other such devices presently being marketed.
A still further object of the present invention is to provide a hydraulic hammer which has an adjustable impact energy.
A still further object of the present invention is to provide a hydraulic hammer which is self-lubricating, thus decreasing maintenance requirements.
Other objects, advantages and features, as well as equivalent structures and methods which are intended to be covered herein, will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims and drawings, in which: